Horn



April 18, 1939- c. s. KELLEY 2,155,232

HORN

Filed June 10, 1936 INVENTOR CECIL S. KELLEY ATTORNEY Patented Apr. 18, 1939 UNITED STATES HORN Cecil S. Kelley, Forest Hills, Pa., assignor to The Westinghouse Air Brake Company, Wilmerding, Pa... a corporation of Pennsylvania Application June 10, 1936, Serial No. 84.410

13 Claims.

This invention relates to an improved pneumatic horn and particularlyto a device of the type employing a vibratory diaphragm.

It is an object of this invention to provide an improved pneumatic horn employing a vibratory diaphragm and in which the diaphragm is of rugged construction and will withstand severe usage without breaking.

A further object of the invention is to provide an improved horn adapted to produce a sound of large volume.

Another object of the invention is to provide an improved pneumatic horn which is operative in response to the supply of fluid under pressure throughout a wide range of pressures.

A further object of the invention is to provide a pneumatic horn of the type employing a vibratory diaphragm and having'a diaphragm constructed of a plurality of laminations of material.

Another object of the invention is to provide a pneumatic horn having a diaphragm which is yieldable in response to variations in the pressure of fluid in a chamber on the face thereof and in which the vibrating portion thereof is of substantially greater weight or mass than the diaphragms now in use so that separate weights attached to the diaphragm are not required.

A further object of the invention is to provide a horn having a diaphragm having a central portion subject to the pressure of the fluid in a chamber and having arms projecting therefrom which are resiliently yieldable. V

Another object of the invention is to provide a pneumatichorn having a resilient vibratory diaphragm subject to the pressure of the fluid in a chamber and having resiliently yieldable means for opposing movement of the diaphragm by the fluid under pressure in the said chamber.

A further object of the invention is to provide a pneumatic horn of the type described and incorporating means to adjustably vary the force exerted by the resiliently yieldable means and opposing movement of the diaphragm.

Another object of the invention is to provide an improved pneumatic horn incorporating means to adjustably vary the tone of the sound produced thereby.

A further object of the invention is to provide an improved pneumatic horn.

Another object of the invention is to provide an improved diaphragm unit adapted for use in pneumatic horns.

Other objects of the invention and features of 55 novelty will be apparent from the following description taken in connection with the accompanyingdrawing, in which:

Fig. 1 is a sectional view of a horn embodying my invention,

Figs. 2, 3 and 4 are elevational views of ele- '5 ments employed in the horn shown in Fig. 1, and

Fig. 5 is a sectional view taken substantially along the line 55 of Fig. 1.

Referring to' the drawing the horn therein illustrated comprises abody I and a cover 2 10; which are detachably secured together by means of cap screws 4. The body I has a bracket portion 5 formed integral therewith byv means of which the horn may be secured to and supported from any suitable support, notshown. 15;

The body I has a substantially annular flange 8 formed thereon and projecting from a face thereof and against which the cover 2 is secured. The cover 2 has formed thereon an annular flange I0 which is adapted to extend within the 20 flange 8 on the body I.

The body I also has formed thereon an annular seat rib I2 which projects from the adjacent portions of the body I and surrounds a chamber I4 which communicates through a 25 choke I6 with a pipe I8 leading from a source of fluid under pressure. There is a chamber I5 outwardly of the seat rib I2 and within the flange 8 on the body I.

A diaphragm device or unit indicated generally by the reference numeral 20 and comprising a plurality of members or laminations, as is best shown in Fig. 1 of the drawing, formed from suitable material, such as sheet metal, is provided. These members or l-aminations are duplicates of each other and each comprises a substantially circular disc having portions of the, margin thereof cut away for a substantial distance,'both radially and circumferenti-ally, le'aving a substantially circular central portion of 40 slightly larger diameter than the seat rib I2 on the'body I and having projecting therefrom at points spaced apart circumferenti'ally thereof radially extending arms 22 which gradually decrease in width away from the central portion, as is clearly shown in Figs. 2 and 5 of the drawing. The arms 22 are of such length that when the diaphragm device 20 is positioned within the flange 8 on the body Ithere is a small amount 50 of clearance between the ends of the arms 22 and the inner face of the flange 8.

The diaphragm device or unit 20 is shown in the drawing as constructed of six thicknesses or laminations of material, but the invention is not limited to this number and a greater or fewer number of laminations may be employed.

The members or laminations of the diaphragm device or unit 20 are secured together by means of {a rivet 24 which extends through holes substanvice 20 engage an annular spacing ring 28 formed of sheet metal or other suitable material and or substantially the diameter of the inner face of r the flange 8 on the body I.

The spacing ring 28 engages a face of a diaphragm 30 which is formed of a piece of suitable resilient material, such as sheet metal, and which 7 is of substantially the diameter of. the innerjface of the flange 8 on the body I.

the diaphragm 30 is engaged by the flange ID on theicover 2; and the various parts of the horn. are

arranged and proportioned sothat when the;

cover 2 is tightly s'ecured: to the body l'bythe cap screws 4 the spacing ring 28 presses against the-iends of the arms ;2-2'on.the:diaphragm device 20 and presses ;the diaphragm device 28,, againstthe' seat rib- I2 anddeflects or bends-the arms 22 slightly as shown in'Figt 1 of the drawing. The diaphragm 3.0 has-an opening 32in the central portion thereof and. this open'ingis of somewhat smallerxdiameter thanfthe central portion of-the diaphragm-device so that the inner margin of the diaphragm'30' overlies the central portion of the. diaphragm device'20; s

The cover 2: hasiai centrally located bore therein: in which is mounteda tubular bushing" 34 which is formed of resilient yieldable material, such" as nio'ulded: rubber; and. which isadapted to engagetheface of the'ldiaphragm 30 adjacent the inner'marginthereof. A sleeve 36 is also po sitioned in the bore in the'cover 2' andz'has'a cylindrical portion: which extends within the tubular bushing 34. Thesle'eve 36 also has a radially extending flanged] thereon which engages the end of thetubular bushing 34', and this flange is; of substantially the diameter of the bore in the cover 2 in which the bushing 34 is located.

The sleeve 36 has adjacent the end thereof 'a portion of smaller diameter than the flange-31 with the passage through the sleeve 36. 'In addition a plurality of passages 42 are formed in the cover 2 and communicate with the chamber 38=and with achamber 44-on therfaceof the diaphragm 30-outwardlyot .thebushing 34. a The cover 2.-also has formed therein a passage. 45 whichcommunicateslwith the chamber 44 adjacent the lowermostportionthereof and with the atmosphere through which moisture may drain from the chamber 44to. the atmosphere. r

V A horn bell'46 provided with a threaded end portion is adjustably secured in the bore in the cover 2 and is held in the adjusted position by means of a lock nut 48. The end of the horn bell "engages the end of the sleeve 36 and acts through thesleev'e 36 to press the resilient bushing 34 against the diaphragm 30 and the force exerted by the bushing 34 on the diaphragm 30 may be adjustably varied by varying the position of th'eghorn bell 46 in'the'cover 2.

- Inbrieration, when'it is desired to blow the The othercface of I8 by suitable means, not shown, and this fluid flows through the choke I6 to the chamber I4 on the face of the diaphragm device 20 within the seat rib I2. At this time the diaphragm device 20 is pressed against the seat rib I2 by the cover 2 acting through the arms 22 of the diaphragm device 20 so that fluid under pressure supplied to the chamber I4 cannot escape therefrom.

'Whenthe pressure of the-fluid in the chamber I4 is increased to a predetermined value, the force exerted by this fluid under pressure on the diaphragm device 20 is sufficient to force the central portion of the diaphragm device 20 away from the seat rib I2 and permit fluid under -pressure'to flow from the chamber I4 past the 1 away from the seat rib I2 fluid under pressure may flow from the chamber I4 to the chamber I5 around the entire periphery of the seat rib I2.

The force-required to move the central portion of the diaphragmdevice 20 awayfrom the seat rib I2 isadeterminedtbythe force required to bendthe arms 22 of the'diaphragm device. These arms are relatively long and narrow and extend throughout ,a portion only ofthe circumference of the diaphragm device and offer muchless resistance to movement of the central portion of V the diaphragm device 20 than would be offered if thelaminations of the diaphragm devicewere complete discs and did not have the portionsintermediate the arms '22 cut away. As a result, therefore, the central portion of the diaphragm device 20 will yield in response to the fcrceexerted thereon by fluid at-moderate pressures in the chamber I4 even though the diaphragm device is constructed of a plurality of laminations.

*When the-central portion of the diaphragm more easily than wouldasingle diaphragm of the same thickness and-mass as this diaphragm devicewhich is built up of several laminations of material. r

- The diaphragm device ZIL'being constructed of several thicknesses of material and having a central portion of substantial diameter, is relatively heavy, andwhen the central portion of the diaphragm deviceis-moved away from the seat rib I2 the inertia of the diaphragmdevice tends to cause thisportion of the diaphragm device to continue to move in this direction even after a reduction in the pressure of the fluid inthe chamber I4 by the escape offluid under pressure therefrom, and a corresponding reduction in the force ISO the flow capacity of the opening across the seat rib I2 is large enough to permit fluid under pressure to escape from the chamber I4 as rapidly as fluid under pressure is supplied thereto through the choke I6, and as a result there will be 'a rapid reduction in the pressure of the fluid in the chamber I4 and a similar'rapid increase in the pressure of the fluidin the chamber I 5.

When the central portion of the diaphragm device 20 is moved away from-theseat rib I2 it engages a portion of the diaphragm 30 adjacent the inner margin thereof so that further movement of the diaphragm device 20 in this direction is opposed by the diaphragm 30 and by the resilient bushing 34.

When the diaphragm device 20 engages the inner marginal portion of the diaphragm 3|] it forms a seal which cuts off communication between the chamber I5 and the atmosphere through the horn bell 46. In addition, as the diaphragm 30 is pressed against the resilient bushing 34 communication between the passage through the horn bell 46 and the chamber 44 is cut ofi.

On an increase in the pressure of the fluid in the chamber I5 as a result of the supply of fluid under pressure thereto from the chamber I4 there is an increase in the force exerted on the diaphragm 30 and tending to move the central portion of this diaphragm against the resilient bushing 34.

The diaphragm 30 being constructed of a single thickness of material is more flexible than the diaphragm device 20 which is built up of a plurality of laminations of material. In addition, the diaphragm 3D has a much larger area subject to fluid under pressure in the chamber I5 than the area on the face of the diaphragm device 20 which is subject to the pressure of the fluid in the chamber I4 so that on a slight increase in the pressure of the fluid in the chamber I5 by flow from chamber I4, to a value substantially below the pressure of the fluid in the chamber I4, the diaphragm 30' is moved farther from its normal position than the diaphragm device 20 is moved away from the seat rib I2 by the fluid under pressure in the chamber I4.

As soon as the pressure of the fluid in the chamber I5 is increased to a relatively low value, therefore, the force exerted by this fluid under pressure on the diaphragm 30 is suflicient to move the diaphragm 30 against the resilient bushing 34 away from the central portion of'the diaphragm device 20 so as to permit fluid under pressure to escape from the chamber I5 to the atmosphere through the opening 32 in the diaphragm 30 and through the horn bell 46.

On an increase in the pressure of the fluid in the chamber I 5, the difference between the pressure of the fluid in this chamber and in the chamber I4 within the seat rib I2 is reduced, and the rate of flow of fluid under pressure from the chamber M to the chamber I5 is correspondingly reduced.

If the rate of supply of fluid under pressure through the choke IE to the chamber I5 is relatively slow, as when the pressure of the fluid supplied to the pipe I8 is at a low value, the central portion of the diaphragm device 20. will be moved a relatively small distance away from the seat rib I2 and fluid under pressure will flow from the chamber I4 to the chamber l5 at a comparatively slow rate to increase the pressure of the fluid in the chamber I5 somewhat and thereby reduce the rate of flow of fluid from the chamber I4 to the chamber I5.

As the central portion of the diaphragm device 20 is moved away from the seat rib I2 onlyv a small distance, it is pressed lightly upon the inner margin of the diaphragm 36 and forces it against the resilient bushing 34 until a small amount of resistance to movement of the diaphragm 3B is developed as a result of the inherent resiliency of the material of which the diaphragm is constructed, and of the force exerted by the resilient bushing 34 and opposing movement of the diaphragm 30.

As there is relatively weak resistance to movement of the diaphragm 30 the pressure of the fluid in the chamber 55 must increase only to a relatively low value before the force exerted by this fluid on the diaphragm 30 is able to move the diaphragm 3B farther against the resilient bushing 34 away from, the diaphragm device 20 so as to permit fluid under pressure to escape from the chamber I5 to the atmosphere, and when the pressure of the fluid in the chamber I5 has been reduced by the escape of fluid therefrom, the diaphragm 30 will move back toward the diaphragm device 2!! to restrict the rate of flow of fluid from the chamber I5 and maintain the pressure of the fluid in the chamber I5 at a predetermined value below the pressure of the fluid in the chamber i4 within the seat rib I2.

If the rate of flow of fluid under pressure through the choke I6 to the chamber I4 is relatively rapid, as when the pressure of the fluid supplied to the pipe I8 is at a comparatively high value, a high pressure will be developed in the chamber I4 and the central portion of the diaphragm device 23 will be moved a relatively great clistance'away from the seat rib I2 and it will engage the inner margin of the diaphragm 3% and press it against the resilient bushing 34 until considerable resistance to movement of the diaphragm 39 is developed.

On movement of the diaphragm device 20 away from the seat rib i2 fluid under pressure flows from the chamber I4 to the chamber 55 and increases the pressure of the fluid in the chamber I5. As there is considerable resistance to further movement of the diaphragm 30 against the resilient bushing 3d at this time, the pressure of the fluid in the chamber i5 must increase to a relatively high value before the force exerted on the diaphragm 3i! is sufficient to move the diaphragm 3G farther against the resilient bushing 34 and away from the central portion of the diaphragm device 2%] to permit fluid under pressure to escape from the chamber IE to the at mosphere through the opening in the diaphragm 3B and the horn bell 4%, while the diaphragm 39 will move back towards the diaphragm device 28 to reduce the rate of flow of fluid under pressure from the chamber I5 to the atmosphere before the pressure of the fluid in the chamber i5 is decreased to the same extent that it is reduced when the rate of supply of fluid under pressure to the chamber i4 through the choke IE is relatively slow and the amount of deflection on the diaphragm device 25 away from the seat rib I2 is relatively small.

It will be seen, therefore, that the pressure of the fluid in the chamber I5 varies with variations in the pressure and the rate of supply of fluid to the chamber I so that the differential between the pressures in the chambers I4 and I5 remains substantially the same regardless of variations in the pressure of the fluid supplied to the pipe #8, and hence the rate of flow of fluid from the chamber M to the chamber I5 will be approximately the same at all times.

Because of the mass of the central portion of the diaphragm device 29, when this diaphragm is set in motion away from the seat rib I2 it continues to move away from the seat rib I2 until a passage is opened to permit fluid under pressure to escape from the chamber I4 to the chamber I5 which is somewhat larger than is required to permit fluid under pressure to escapefrom the chamber I4'to reduce thepressure of the fluid in this chamber to a value such that the force exerted by the fluid in thechamber I4 on the diaphragm device 29 is unable to'maintain the diaphragm device in the position to which it has been moved.

As the diaphragm device moves to a position to open a relatively large passage across the seat rib I2, fluid underpressure will be released from the chamber I4 at a relatively rapid rate so that the pressure of the fluid in the chamber I4 is quickly reduced to a value insufficient to maintain the central portion of the diaphragm device 23 in the position to which it'has been moved, and. the diaphragm device 20 is thereupon moved back towards the seat rib I2 due to the inherent resiliency of the material of which it is constructed.

' When the central portion of the dlaphragm device 20 is moved towards the seat rib I2 the inertia of this portion of the diaphragm device causes it to continue to move in: thi'sdirection until it engages the seat rib I2, and thereby cuts off the release of fluid-under pressure from the chamber I4 past the seat rib I2 to the-chamber I5.

On this movement of the central portion of the diaphragm device 20, the central portion thereof is moved away from the inner margin of the diaphragm and thefluid in the chamber I5 may escape at a rapid rate to the atmosphere through the opening 32 in the diaphragm and through the horn bell 46.

The resilient bushing 34 remains in sealing engagement with the face of the diaphragm 30- during'these movements of the diaphragm 30, and of the diaphragm device 20, and prevents the flow of fluid from the passage'in the horn bell 46 to the chamber 44 on the face of the diaphragm 30 outwardly of the bushing 34 where it might'interfere with the movement of the diaphragm 30 by the fluid under pressure in the chamber I5.

The volume of the chamber 44 varies with movement of the diaphragm 30 and fluid under pressure may flow to or from this chamber at restricted rates through the passages 42 in the sleeve 36, the chamber 38 and the passages 42 in the cover 2, or through the drain passage 45. The passages 42 and 45 also provide meansfor the escape of fluid'under pressurefrom the chamber 44 in case any fluid under pressure flows from the horn bell past the resilient bushing 34 to the chamber 44.

When the diaphragmvdevice 20 is moved back into engagement with the seat rib I2 and the escape of fluid under pressurefrom the chamber I4 is cut off, the pressure of the fluid in this a chamber increases because of the continued supply of fluid under, pressure thereto through the choke l5. Because of the relatively small volume of the chamber I4, the pressure of the fluid in this chamber is quickly increased to a value such that the force exerted on the diaphragm device 20 is sufiicient to overcome the forcetending to 'hold the central portion of the diaphragm device 20 in engagement with the seat rib I2. The diaphragmdevice 20 will thereupon be movedaway fromthe seat rib' I2 to again permit fluid under pressure to escape from the chamber I4 to the chamber I5'and the cycle of operation: described above is repeated. V

The movements of the central portion of the diaphragm device 20 out of engagement with the seat rib I2 and into engagement therewith occur very rapidly and result in the creation of a rapid series of vibrations in the air column within the horn bell 46 with the result that an audible sound is produced.

The pitch of the note produced by the horn is determined by the length of the horn bell, and the rate of vibration of the diaphragm device 20-must be in tune with the rate of vibrations of the air column in the horn bell 46 in order for the horn to operate most effectively and give a sound 0 maximum volume and clarity of tone.

The rate of vibration of the diaphragm device 20 is regulated by the rate at which fluid under pressure may escape from the chamber I4to the chamber I5 and therefrom to the atmosphere through the opening 32in the diaphragm 30 and the passage through the horn bell 46.

The release of fluid under pressure from the chamber I5 may be varied by varying the adjustment of the horn bell 46 in the cover '2, and thereby varying the force exerted by the resilient bushing 34 on the diaphragm 30 and opposing movement of the diaphragm 30 by the fluid under pressure in the chamber I5. This also varies the pressure to which the fluid in the chamber I5 must be increased before fluid under pressure is released therefrom and thereby" influences the diiference between the pressure of the fluid in the chamber I5 and in the chamber I4, and thus influences the rate of flow of fluid from the chamber I4 which governs the vibrations of the diaphragm device 20.

'While one embodiment of the improved pneumatic horn and diaphragm provided by my invention has been illustrated and described in detail, it should be understood that the invention is not limited to these details of construction and that numerous changes and modifications may be made without departing from the scope of the following claims.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is: I

1 Ina sound producing device, in combination, a casing having a chamber therein, a vibratory diaphragm device mounted in said chamber, means for causing said diaphragm device to vibrate, said diaphragm device comprising a plurality of laminations of material, each of the laminations of the diaphragm device having a central portion and having projecting therefrom radially extending arms, and a member engaged by the ends of said arms whereby said arms are flexed upon movement of said diaphragm device.

2. In a sound producing device, in combination, a casing having a chamber therein, a vibratory diaphragm device mounted in said chamber, means for causing said diaphragm device to'vibrate, said diaphragm device comprising a plurality of laminations of material, each of the lam'inations of the diaphragm device having a central portion and having projecting therefrom radially extending arms, said arms decreasing in width away from the said central portion, and a member engaged by the ends of said arms whereby said arms are flexed upon movement of said diaphragm device. I 1 3. In a sound producing device, in combina tion, a casing section having a seat rib associated therewith, a'diaphragm device formed of a plurality of laminations each having a central portion and having arms extending radiallytherefrom, the central portion of the lamination on one face of the diaphragm device being of larger diameter than the said seat'rib and being adapted to engage said seat rib, means engaging the other face of the diaphragm device adjacent the ends of the said arms for pressing the diaphragm device into engagement with said seat rib, and means for supplying fluid under pressure to the area'within said seat rib.

4. In a sound producing device, in combination, a casing section having a seat rib associated therewith, a diaphragm device formed of a plurality of laminations each having a central portion and having arms extending radially therefrom, means extending through openings located substantially centrally of said laminations for securing said laminations together, the central portion of the lamination on one face of the diaphragm devicebeing of larger diameter than theseat riband being adapted to engage said seat rib, means engaging the other face of the diaphragm device adjacent the ends of the said arms for pressing the diaphragm device into engagement with said seat rib, and means for supplying fluid under pressure to the area within the said seat rib.

5. In a sound producing device, in combination, a casing section having a seat rib associated therewith, a diaphragm device formed of a plurality of laminations each having a central portion and having arms extending radially therefrom, the central portion of the lamination on one face of the diaphragm device being of larger diameter than the said seat rib and being adapted to engage said seat rib, means engaging the other face of the diaphragm device adjacent the ends of the said arms for pressing the diaphragm device into engagement with said seat rib, and means for supplying fluid under pressure at a restricted rate to the area within said seat rib.

6. In a sound producing device, in combination, a casing section having a seat rib associated therewith, a diaphragm device formed of a plurality of laminations each having a central portion and having arms extending radially therefrom, the arms decreasing in width away from said central portion, the central portion of the lamination on one face of the diaphragm device being of larger diameter than the said seat rib and being adapted to engage said seat rib, means engaging the other face of the diaphragm device adjacent the ends of the said arms for pressing the diaphragm device into engagement with said seat rib, and means for supplying fluid under pressure to the area within said seat rib.

'7. In a sound producing device, in combination, a casing having a chamber therein and having a seat ribassociated therewith and projecting into said chamber, means for supplying fluid under pressure to the area within said seat rib, a diaphragm device mounted in said chamber and adapted to have a face thereof engage said seat rib, the diaphragm device being subject to the pressure of the fluid within the seat rib and controlling the flow of fluid under pressure from the area within said seat rib to the chamber in said casing outwardly thereof, a diaphragm element subject to the pressure of the fluid in'said chamber, said diaphragm element being movable relative to the diaphragm device by the fluid in said chamber, and means controlled by said diaphragm device and by said diaphragm element for releasing fluid under pressure from said chamber.

8. In a sound producing device, in combination, a casing having a chamber therein and having a seat rib associated therewith and projecting into said chamber, means for supplying fluid under pressure to the area within said seat rib, a diaphragm device mounted in said chamber and adapted to have a face thereof engage said seat rib, the diaphragm device being subject to the pressure of the fluid in the area, within the seatriband controlling the flow of fluid under pressure fromthe area within said seat rib to the chamber in said casing outwardly thereof, a diaphragm element subject to the pressure of the fluid in said chamber, said diaphragm element being movable relative tothe diaphragm device by the fluid in said chamber, and means responsive" to relative movement between said diaphragm device and said diaphragm element for releasing fluid under pressure from said chamber.

9 In a sound producing device, in combination, a casing having a chamber therein and having a seat rib associated therewith and extending into said chamber, two diaphragm units mounted in said chamber, one of said diaphragm units having a face adapted to engage the seat rib, said diaphragm unit being subject to the pressure of the fluid in the area within said seat rib and controlling the flow of fluid under pressure from the area within said seat rib to the chamber in said casing outwardly thereof, said diaphragm unit being arranged to be deflected a given distance from the seat rib on an increase in the pressure of the fluid within said seat rib toa given value, the other of said diaphragm units being subject to the pressure of the fluid in said chamber outwardly of said seat rib and being arranged to be deflected farther than said given distance on an increase in pressure of the fluid in said chamber to a value less than said given value, and means controlled by relative movement of said diaphragm units for releasing fluid under pressure from said chamber.

10. In a sound producing device, in combination, a casing having a chamber therein and having a seat rib associated therewith and projecting into said chamber, means for supplying fluid under pressure to the area within said seat rib, a diaphragm device mounted in said chamber and adapted to have a face thereof engage said seat rib, the diaphragm device being subject to the pressure of the fluid in the area within said seat rib and controlling the flow of fluid under pressure from the area within the seat rib to the chamber 'in said casing outwardly thereof, a diaphragm element subject to the pressure of the fluid in said chamber, means yieldingly opposing movement of said diaphragm element by the fluid in said chamber, and means controlled by said diaphragm device and said diaphragm element for releasing fluid under pressure from said chamber.

11. In a sound producing device, in combination, a casing having a chamber therein and having a seat rib associated therewith and projecting into said chamber, means for supplying fluid under pressure to the area within said seat rib, a diaphragm device mounted in said chamber and adapted to have a face thereof engage said seat rib, the diaphragm device being subject to the pressure of the fluid in the area within said seat rib and controlling the flow of fluid under pressure from the area within the seat rib to the chamber in said casing outwardly thereof, a diaphragm element subject to the pressure of the fluid in said chamber, biasing means yieldingly opposing movement of said diaphragm element by the fluid in said chamber, means to adjustably vary the force exerted on said diaphragm element by said biasing means, and

' tion, a casing; having a chamber thereinand having a seat rib associated therewith and pro! Jecting-int said am m an for supplyin fluid underpressure to the .area within said seat rib, a'diaphragm. device mounted in said chamber and adapted to have a face thereof engage said seat rib, thediaphragm device being subject to the pressure of the fluid in the area within said seat rib and controlling the fiow of fluid under pressure from, the areawithin the seat rib to the chamberin said casing outwardly of the seat "r'ib,-a diaphragm element subject to the pressure o thsfluidin sa d. ch ber, said d ph a m e emer t being -movable relative to the diaphragm device by the =fluid in said chamber, said diaphragm element having an opening substantially centrally thereof,zthe face of the diaphragm element surrounding said opening being adaptedto be engaged by the diaphragm device to control communication between said chamber and said opening. V

13.A diaphragm device for use in a signaling device and having relatively large mass together with a high degree of flexibility, the diaphragm device comprising'a plurality of thicknesses of material each having a central portion providing a large mass and having radially extending arms projecting therefrom providing a hig-hdegree of flexibility.

CECIL'S. KELLEY. 

